Long-Term Variability in Methane in Domestic Water Wells in Northeast Pennsylvania

Transcription

1 GROUNDWATER & ENVIRONMENTAL SERVICES,INC. Charles Whisman, PE Richard Wardrop, PG Debby Yost Bert Smith, PG Long-Term Variability in Methane in Domestic Water Wells in Northeast Pennsylvania Denise Good, PE Principal Engineer GES

2 Study Background Methane (CH 4 ) Prevalence and Variability Lack of water well construction standards General findings from extensive pre-drill data Water well samples collected ( ): 11,312 Methane detections (>0.026 mg/l): 2,740 (24.2%) >0.026 to 3 mg/l: 2,064 (18.2%) >3 to 7 mg/l: 287 (2.5%) >7 to 20 mg/l: 270 (2.4%) >20 mg/l: 119 (1.1%) Limited understanding of natural methane variation and occurrence related to complaints

3 Long-Term Monitoring: Domestic Wells Address gaps in understanding Quantify natural variation in methane levels Relevance Significant importance in assessing natural methane variation and occurrence Study Objective Gain understanding of long-term variability of methane in domestic water wells and correlation to other parameters, such as well usage and pumping

4 Study Design 11 domestic water wells Pre-drill (baseline) sampling data used to select sites 3 categories of baseline dissolved methane levels Low: < 5 mg/l Medium: 5 to 15 mg/l High: > 15 mg/l 3-4 wells from each category Depths: 40 to 300 feet Located across Bradford and Sullivan Counties in Northeastern Pennsylvania 12 months of monitoring

5 Study Locations

6 General Outline: Study Parameters Local and Regional Geology Supply Well Construction and Conditions Manual Water Sampling for Laboratory Analysis No dissolved methane sensor available Continuous Remote Monitoring Headspace gas parameters (CH 4, CO 2, O 2 ) Water well parameters (water levels, turbidity) Weather Parameters Data logged and manually downloaded (temperature, barometric pressure, humidity, wind, precipitation)

7 Preparation of Study Water Wells Water treatment system installation or upgrade Borehole geophysics Downhole InSitu water quality logging (ph, temp., cond.) Supply well power re-configuration Jet pumps replaced with submersible pumps (2 wells)

8 Remote Real-Time Monitoring Parameters Well Headspace CH 4 (10 ppm to 100% volume, 2 sensors) O 2 CO 2 Gas flow Gas pressure Down Well Water level Turbidity Pump flow rate

9 Real-Time Data Data logged every minute Transferred via cell modem Uploaded to custom software Uploaded to secure website Choose location via list or map Graphs, statistics, raw data Data integrated with Microsoft Access, EarthSoft EQuIS and other data management tools 9

10 Equipment Setup Equipment customized at each site Headspace gas drawn from ~2 feet below well grade using sample pump Weather Stations at 6 locations Barometric pressure Precipitation Temperature Wind Humidity

11 Water Type and Geologic Setting Location Mapped Bedrock Formation Water-Type MB Lock Haven Sodium - Bicarbonate T Lock Haven Sodium - Bicarbonate B Lock Haven Sodium - Bicarbonate DV Catskill Sodium - Bicarbonate/Chloride G Lock Haven Sodium/Calcium -Bicarbonate V Catskill Sodium/Calcium -Bicarbonate N Catskill Sodium/Calcium -Bicarbonate TB Lock Haven Sodium - Chloride H Catskill Sodium - Chloride R Lock Haven Sodium - Chloride EH Catskill Calcium/Sodium - Bicarbonate

12 Analytical Data Assessment Tracking data to determine relationships with methane and key dissolved constituents: Sulfate Chloride Methane and Sulfate in Water: Site R Barium Lithium Strontium

13 Variation in Dissolved Methane in Groundwater Dissolved Methane Variability: Site EH EH Location Methane, mg/l Baseline Sample

14 Dissolved Methane Variation: Low Level (<5 mg/l) Baseline Baseline Baseline Baseline

15 Dissolved Methane Variation: Medium Level (5-15 mg/l) 30 Changes in Dissolved Methane in Groundwater at "Medium" (5-15 mg/l) Level Locations EH Methane, mg/l KB LH V Baseline Baseline 5 0 Baseline

16 Dissolved Methane Variation: High Level (>15 mg/l) Baseline Baseline

17 Turbidity vs Water Level: Site B Turbidity, NTU Turbidity Water Level /4/2012 0:00 2/4/ :00 2/5/2012 0:00 2/5/ :00 2/6/2012 0:00 2/6/ :00 2/7/2012 0:00 Water Level Change from Initial Static, ft

18 Headspace Methane vs. Water Level Change in 24 Hours EH Location Headspace Methane vs Water Level: 24 Hours (Site EH) Methane, ppm /5/2011 6:00 12/5/2011 8:24 12/5/ :48 12/5/ :12 Headspace Methane 12/5/ :36 12/5/ :00 Water Level Change 12/5/ :24 12/5/ :48 12/6/2011 1:12 12/6/2011 3: /6/2011 6:00 Water Level Change from Initial Static, ft

19 Observing Methane Trends over Different Time Intervals Methane, ppm Headspace Methane vs. Water Level Change in 24 Hours EH Location 550 Headspace Methane Water Level Change 1 Day Duration Water Level Change from Initial Static, ft Methane, ppm Headspace Methane vs. Water Level Change in 72 Hours EH Location 550 Headspace Methane Water Level Change 3 Day Duration Water Level Change from Initial Static, ft /30/2012 0:00 6/30/ :00 7/1/2012 0: /30/2012 0:00 7/1/2012 0:00 7/2/2012 0:00 7/3/2012 0:00 Methane, ppm 550 Headspace Methane Headspace Methane vs. Water Level Change in 7 Days EH Location Water Level Change 7 Day Duration Water Level Change from Initial Static, ft /30/2012 0:00 7/1/2012 0:00 7/2/2012 0:00 7/3/2012 0:00 7/4/2012 0:00 7/5/2012 0:00 7/6/2012 0:00 7/7/2012 0:00

20 Headspace Methane vs. Water Level Change in 6 Hours DV Location Headspace Methane vs Water Level: 6 Hours (Site DV) Methane, ppm Headspace Methane Water Level Change /12/ :00 5/12/ :12 5/12/ :24 5/12/ :36 5/12/ :48 5/12/ : Water Level Change from Initial Static, ft

21 Comparison Between Groundwater Methane vs. Headspace Methane Over Time Headspace Methane vs Dissolved Methane: Site EH Groundwater Methane Headspace Methane Groundwater Methane mg/l Headspace Methane ppm /12/ /24/ /01/ /08/ /01/ /15/ /28/ /12/ /26/ /09/ /23/ /06/ /22/ /02/ /19/2012 5/3/2012 5/17/2012

22 Variability in Headspace Methane over Time: Site EH January 2012 Methane, ppm April 2012 July 2012 July 2012 October 2012

23 Headspace Methane vs Air Temperature Sites LH and N N LH 5 mi Methane, ppm Air Temp, deg F Sites LH and N are ~5 miles apart Note: All data is preliminary

24 Headspace Methane across Multiple Locations Sites N, V, and T T N Methane, ppm (Sites N and T) Note: Correlation appears climate/weather related 5 mi V Methane, ppm (Site V) Site T is ~35 miles northwest of Sites N and V Sites N and V are ~5 miles apart Note: All data is preliminary

25 Headspace Methane across Multiple Locations Sites LH, R, and T T R LH Methane, ppm Note: Correlation appears climate/weather related 5 mi Site T is 35 miles northwest of Site LH and 7 miles east of Site R Site LH is miles 32 southeast of Site R Note: All data is preliminary

26 Headspace Methane vs Air Temperature and Wind Speed: Site G Wind Speed, mph Methane, % Volume Air Temperature, deg F. 0.5% Vol = 5,000 ppm = 10% LEL Note: All data is preliminary

27 Headspace Methane vs Humidity: Site G Methane, % Volume Humidity, % 0.5% Vol = 5,000 ppm = 10% LEL Note: All data is preliminary

28 Headspace Methane vs Water Temp vs Air Temp vs Water Level: Site G 0.5% Vol = 5,000 ppm = 10% LEL Note: All data is preliminary

29 Methane vs Carbon Dioxide Well Headspace: Site MB Methane, % Volume Carbon Dioxide, ppm 0.5% Vol = 5,000 ppm = 10% LEL Note: All data is preliminary

30 Headspace Methane vs Barometric Pressure Methane, ppm Barometric Pressure, in Hg Note: All data is preliminary

31 Headspace Methane vs Barometric Pressure Methane, ppm Barometric Pressure, in Hg Note: All data is preliminary

32 Preliminary Findings Methane occurs naturally and highly variable: Spatially and temporally Weather (temperature, barometric pressure, wind, humidity, drought) Man-induced changes (water well pumping) Single pre-drill baseline methane sample may not represent the full range of natural variability Natural methane levels (headspace and dissolved) may be influenced by pumping or water level fluctuations Water level declines (pumping or natural) may increase natural methane headspace concentrations

33 Preliminary Findings (continued) Natural methane levels in well headspace may correlate with: air temperature, wind, and humidity changes CO 2 fluctuations barometric pressure changes Observed correlation of natural headspace methane levels across multiple well locations (influenced by weather) including wells located 5 to 40 miles apart Natural methane concentrations may vary seasonally Technical journal publications under preparation

34 GROUNDWATER & ENVIRONMENTAL SERVICES,INC. Charles Whisman, PE Richard Wardrop, PG Thank You! Debby Yost Bert Smith, PG Real-Time Monitoring for Evaluating Methane Variability in Domestic Water Wells Denise Good, PE Principal Engineer GES